The present invention is directed to melt processable, high molecular weight polyphosphonates having a high refractive index and methods of preparing the same.
Polycarbonates are tough, rigid engineering thermoplastics. They are melt-processable and can easily be formed into optical and ophthalmic products by injection molding, instead of more time consuming and expensive casting processes. There is increasing demand for high refractive index materials for optical and opthalmic products. Polycarbonates, however, have only a limited refractive index.
Thus, there is a need for melt processable materials which have high refractive indices.
The present invention provides high molecular weight, film forming, high refractive index, melt-processable polyphosphonates. These polymers typically have lower melt processing temperatures and birefringerence than polycarbonates. These polymers may be used to form optical or ophthalmic products, such as lenses. Furthermore, the polymers of the present invention can be transferred directly from a reactor to a final mold for, for example, ophthalmic lens production, increasing the economic efficiency of the lens manufacturing process.
Another embodiment of the invention is a method of preparing the polyphosphonates of the present invention.
The present invention encompasses melt-processable phosphonate homopolymers or copolymers comprising, consisting essentially of, or consisting of units of the formula: 
wherein R1, R2, and R3 are independently O or S; at least one of R1, R2, and R3 is S; R4 is a linear or branched C1-C4 alkyl or C1-C4 haloalkyl, phenyl, chlorophenyl, p-tolyl, benzyl, biphenyl, or cyclohexyl; and R5 is 
or any combination of any of the foregoing. R1 and R3 are preferably O. Preferably, R2 is S. Preferably, R4 is phenyl. R5 is preferably 
or any combination of any of the foregoing.
Another embodiment of the present invention encompasses melt-processable phosphonate homopolymers or copolymers comprising, consisting essentially of, or consisting of units of the formula: 
wherein R6, R7, and R8 are independently O or S; R9 is a linear or branched C1-C4 alkyl or C1-C4 haloalkyl, phenyl, chlorophenyl, p-tolyl, benzyl, biphenyl, or cyclohexyl; and R10 is 
Preferably, R6 and R8 are O.
The invention further includes an optical or ophthalmic part, preferably a lens, comprising, consisting essentially of, or consisting of melt-processable phosphonate homopolymers or copolymers comprising units of the formula: 
wherein R11, R12, and R13 independently are O or S; R14 is a linear or branched C1-C4 alkyl or C1-C4 haloalkyl, phenyl, chlorophenyl, p-tolyl, benzyl, biphenyl, or cyclohexyl; and R15 is defined as R5 above. The optical or ophthalmic part may also be a transparent or translucent sheet comprising the melt-processable phosphonate polymers of formula III.
The polymers of the present invention can be homopolymers or copolymers, including, but not limited to, random copolymers and block copolymers. A preferred copolymer comprises a first unit having the formula 
where R16, R17, and R18 are independently O or S; R19 is phenyl; and R20 is 
and a second unit having the formula 
where R21, R22, and R23 are independently O or S; R24 is phenyl; and R25 is 
The number average molecular weight of a homopolymer or copolymer of the present invention is typically from about 10,000 to about 60,000 g/mol and preferably from about 15,000 to about 40,000 g/mol.
Generally, these homopolymers and copolymers have a glass transition temperature (Tg) greater than or equal to about 120xc2x0 C. Also, these polymers typically have a refractive index ranging from about 1.58 to about 1.64. These polymers are typically processable at from about 75 to about 100xc2x0 C. above their glass transition temperatures.
The melt-processable phosphonate homopolymers and copolymers of the present invention may be prepared as described in Japanese Patent Publication No. 61-261321. One method of preparing these polymers is as follows. At least one phosphonic acid halide having the formula 
where R26 and R28 are independently halogens; R27 is O or S; and R29 is a linear or branched C1-C4 alkyl or C1-C4 haloalkyl, phenyl, chlorophenyl, p-tolyl, benzyl, biphenyl, or cyclohexyl is reacted with one or more bisphenols to yield the phosphonate homopolymer or copolymer. Preferred phosphonic acid halides include phenyl phosphonic dichloride, phenyl thiophosphonic dichloride, and any combination of any of the foregoing. The phosphonic acid halide may be dissolved by mixing it in a solvent, such as methylene chloride, prior to reacting the phosphonic acid halide with the bisphenol. When preparing polymers having units of the formula I or II above, R27 and R29 of the phosphonic acid halide are defined as R2 and R4 or R7 and R9 above, respectively.
Suitable bisphenols include, but are not limited to, hydroquinone; resorcinol; 4,4xe2x80x2-dihydroxybiphenyl; 4,4xe2x80x2-cyclohexylidenediphenol; bisphenol A; bis(4-hydroxyphenyl)methane; 2,2-bis(2-hydroxyphenyl)propane; bis P; 4,4xe2x80x2-bis-S; 2,2xe2x80x2-bis-S; 2-hydroxyphenyl-4xe2x80x2-hydroxyphenyl sulfone; dihydroxydiphenyl ether; bis(4-hydroxyphenyl)sulfide; bis(2-hydroxyphenyl)sulfide; dihydroxybenzophenone; 1,5-dihydroxynaphthalene; 2,5-dihydroxynaphthalene; 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; thiodithiophenol; phenolphthalein; 4,4xe2x80x2-bis(hydroxyphenyl)phenyl phosphine oxide; xcex1,xcex1xe2x80x2-bis(4-hydroxy-3-methylphenyl)-1,4-diisopropylbenzene; bis E; 2,2-bis(4-hydroxy-3-methylphenyl)propane; bis(4-hydroxy-3-methylphenyl)sulfide; dihydroxydiphenylether; 1,3-bis(4-hydroxyphenoxy)benzene; phenyl HC; t-butyl HQ; 4,4xe2x80x2-thiobis(t-butyl cresol); 2,2xe2x80x2-thiobis(4-t-octylphenol); and any combination of any of the foregoing. The bisphenol may be dissolved by mixing it in a solvent, such as methylene chloride with triethylamine and 1-methyl imidazole, prior to reacting the bisphenol with the phosphonic acid halide.
The copolymer of the present invention may be prepared by reacting at least two different phosphonic acid halides having the aforementioned formula with one or more bisphenols. Alternatively, the copolymer may be prepared by reacting at least one phosphonic acid halide with at least two different bisphenols.
Optical or ophthalmic lenses may be prepared by injection or compression molding a melt-processable phosphonate polymer of the present invention into the form of a lens.
The following examples illustrate the invention without limitation.